A nurse is overseeing the care of multiple newborns in a neonatal unit. One newborn, whose mother had poorly controlled gestational diabetes, exhibits lethargy, poor feeding, jitteriness, and a respiratory rate of 72 breaths per minute. Which action should the nurse take first?

Infants of mothers with poorly controlled gestational diabetes are at high risk for neonatal hypoglycemia because fetal hyperinsulinism develops in response to chronic maternal hyperglycemia, and once the glucose supply from the placenta ceases at delivery, excessive insulin drives blood glucose dangerously low. The constellation of symptoms described — lethargy, poor feeding, jitteriness, and tachypnea — are classic signs of neonatal hypoglycemia. Because assessment must precede intervention, checking the blood glucose level is the correct first action; it confirms or rules out hypoglycemia and guides subsequent management. Without a confirmed glucose value, other interventions are premature or could be misdirected. Notifying the charge nurse about possible sepsis is not warranted as the first action when the clinical history so strongly points to hypoglycemia; sepsis workup may follow if glucose is normal. Encouraging feeding could help mild hypoglycemia but should only be implemented after glucose is confirmed low; feeding without assessment skips a critical step. Administering oxygen addresses the tachypnea symptom but not the underlying cause, and tachypnea in a hypoglycemic newborn will resolve when glucose is corrected. Therefore, glucose measurement is the priority first step following the nursing process: assess before intervening.